Inhibitor



atenied ar. 31, 1%42 Philip Sublrow, Log Angel'es, Calif.

No Drawing. Ap lication March 12, 1940, Serial No. 323,582

8 Claims.

This invention relates to lubricating oils and greases and particularly to lubricating oils and greases to which addition agents have been added for the purpose of improving the stability of the lubricating oil under the' conditions of oxidation in use. It also relates to lubricating oils to which addition agents have been added for the purpose of reducing the corrosion of bearings occasioned by the use of lubricating oil, and also relates to the addition agents for lubricating oils in order to improve the color stability and to improve the lubricating properties of lubricating oils and greases.

Sulfur has a beneficial effect in inhibiting X- idation and in preventing corrosion of cadmiumsilver and lead-copper bearing alloys when employing lubricating oil. Thus, sulfur in the form of thio-ether or sulfides, disulfide or polysulfide form is particularly efficacious.

Sulfur in the above forms, besides itself being efficacious as an inhibitor against oxidation and as a corrosion inhibitor in lubricating oils, has the beneficial property of: imparting activity at relatively high temperature and imparting stability to the compound at such relatively high temperatures.

This beneficial property is also extended to other inhibitor groups in a compound, e. g., compounds containing inhibitor groups such as hydroxy groups, amino groups or other sulfide, disulfide or polysulfide groups. The introduction of such additional sulfur grouping imparts activity and stability to the compound at the higher temperatures.

This property of relatively high temperature stability of. the sulfur grouping is particularly important in Diesel engine lubrication where high temperatures are attained on the piston and on the cylinder linings. In lubrication of such engines, as well as in motor lubricating, this property is useful in inhibiting the corrosion of alloy bearings which are coming into wide use in both gasoline and Diesel engines.

I propose, as an inhibitor for these and like purposes, compounds of the following formulations: RrRxR; RzrRrRD; or DRrRxRD in which R is an aryl or :alkyl aryl, or a substituted aryl or alkyl aryl group, :1: is a sulfur, oxygen or telluriurn, but preferably a sulfur group, R is an alkyl or substituted alkyl group and D is an inhibitor group taken from the class of hydroxy. amino, sulfide,"'disulflde or polysulfidergroups.

,As an example of the type of compound which I wish to employ, I suggest:

2,5 dirnethyl hexane-2,5-bis(p-toly1 sulfide) This compound may be formed by the reaction of para thio-cresol and 2,5 dichloro-2,5-dimethyl hexane in the presence of aluminum chloride. I may also use the product produced by the reaction in the same manner of chic-phenol or with ortho, para or meta cresol with 2,5-dichloro-2,5-dimethyl hexane:

(CH3)2C(C1)CH2CH2(C1) C(Cl-Iz) 2 or with 2,5-dimethyl-1,5-hexadiene:

CH2=C(CH3) CH2CH2(CH3) (3:61-12 in the presence of aluminum chloride or boron trifluoride as a catalyst. These reactions and the process to be employed are described in the Journal of the American Chemical Society, January 1940, pages 36-48 inclusive.

The reactions thus employed will give the corresponding'thio-ether of the general formula:

sulfur is joined to an alkyl 'or aromatic and also to the carbon of the thio-phenol. We would have the corresponding substituent compounds, as for instance:

CH: CH: oHaQs-+--o1rronr- -s@cm N52 on. on; NH,

or corresponding compounds, but wherein but one of the aryl or alkyl aryl carries the substituent, OH, N'Hz or CzHe-S.

The action of sulfur in reinforcing the action of other inhibitor groups also manifests itself in inhibitor compounds in which the sulfur is directly joined to two ring carbons as in the case of phenyl thio-ethers or in the case of diphenyl disulfides or dibenzyl disulfide. In such compounds the beneficial action of the sulfur group may be imparted-to diverse inhibitor groups which are joined to the phenyl radical. Thus the presence of both the NH: and the OH group in a compound gives to the compound beneficial properties arising from the simultaneous presence of both groups, e. g. compounds of the general formula DRSRD or DRSS-RD where R; is an aryl, alkyl or arylalkvl group and D is an inhibitor group taken from the group such as the OH, NH: or sulfide or polysulfide group.

Thus, compounds of such general formula conhydroxy phenyl or resorcyl group may be synthesized by the methods disclosed in Journal of the American Chemical Society, vol. 60, page 2729 etc. (1938) or by the methods disclosed in the Journal of the American Chemical Society, vol. 56,'page 1978 et seq. (1934).

The following compound may thus be formed:

scribed in the above articles by the following reactions:

NOzCsH4-SS-CsH4NOa may be made by either of the following reactions as described in the foregoing articles:

I may also employ as an inhibitor for the same purpose the corresponding amino compound obtained by reduction of the nitro compound, to-wit:

In inhibitors having a phenol or cresol grouping the OH has acidic properties. Such groups have corrosive properties in themselves and while. they inhibit the corrosion of the alloy bearings by inhibiting oxidation of the lubricating oil; they are themselves corrosive due to their acidity. The OH groupings also have, in some compounds, the property of limiting the oil solubility of the compound. The corrosivity may be retarded and oil solubility increased by neutralizing the OH with lime to form the corresponding calcium soap. However in use, some decomposition and. some hydrolysis occurs, liberating the acid group.

The presence of the NH: group will have the property of reducing this acidity while itself imparting inhibitor action to the compound.

v taining amido phenyl or amido phenol group and Compounds of the formulations'D'RSRD and D'P.S +RD where R is an aryl, or aryl alkyl group and D is an NH: group and D is an OH group joined to a ring carbon, have the above properties and examples of such compounds are given above. Y

' These compounds may be' dissolved in the lubricating oil and if they have acidic substituents, such as hydroxy group, may be converted into corresponding calcium soaps by saponification with calcium hydroxide. These compounds or their soaps may be employed by adding them to lubricating oil and/or grease in the order of from .05 to 1% by weight, moreor less. They may be compounded along with other addition agents, as for instance, with the calcium soap of chlorinated stearic or palmitic acid, such as calcium dichlorostearic acid to form a Diesel engine lubricating oil which, while non-corrosive, will prevent ring sticking, be stable against oxidation ,and degradation." Instead of the chlorinated fatty acid soapwe may use the calcium soap of phenyl stearic acid. An oil carrier such as a I This may be synthesized by the methods de purified naphthenic lubricating oil or a purified lubricating oil produced from a paramnic oil is employed. Preferably I prefer to use naphthenic base oil. The calcium soap of the dichlor stearic acid, or the calcium soap of phenyl stearic acid or other soap used for the prevention of ring sticking, such as, the soap of acids produced by the oxidation of petrolatum, is incorporated in liibricating oil in the order of from .1% to 2% more or less, depending upon the character of the soap, the oil employed and the amount of ring sticking to which the oil may be subjected. To this may be added from .05% to 2% bf the compounds herewith suggested. The addition agent may be added to motor lubricants which show a tendency to corrosion of cadmium-silver bearings and of copper-lead bearings, to prevent the corrosion of such bearings by such oil in use. The compounds may be used in the proportion depending upon the oil to which they are being added and the degree of corrosion occasioned by such oil.

It may be desirable to add, in addition to such compounds, and in addition to the calcium soap or calcium stearic acid or of the dichlor stearic acid or the calcium soaps produced by oxidation of lubricating oil or petrolatum, a small amount of the calcium soap of a weak acid as for instance, oleic acid or stearic acid or palmitic acid. The purpose of this small amount of soap is to act as a solubilizing product to increase the compatibility of the oil with the addition agents employed and to increase the amount of calcium ions present in the mixture in order that as the oil is used and the acidity generated on use, either by the oxidation of the oil o'r liberation of the acids introduced as soaps, the reserve alkalinity introduced by means of the soap of the weak acid acts to combat this generated acidity. Theamount of ;such soap to be added will vary with 'the oil and the addends and the formulations will be obvious to those skilled in the art, from what .has been said before.

As a practical matter, it will be desirable to first make a concentrate of the inhibitor and soaps which are to be added to the lubricating oil, in a concentration in excess of the concentration to be-finally. used, for instance, in a concentration of 5 to 50 or more percentage. This concentrate may then be mixed in the required proportion with the lubricating oil to be compounded.

Without limiting the generality of the invention herein disclosed the following is an example of the formulation which may be used.

A mineral oil having the properties of a well treated naphthenic base lubricating oil is compounded with 15% to 30% by weight of the calcium soap of chlorinated stearic acid preferably formed by reaction of lime with chlorinated stearic acid containing about 1'7 to 22% chlorine by weight and carries from 5% to 30% by weight of one of the following compounds:

2,5-dimethyl hexane-2,5-bis(p tolyl sulfide) 2,5-dimethyl hexane-2,5-bis phenyl sulfide Amido phenyl hydroxy phenyl sulfide Amido phenyl resorcyl sulfide Bis amido phenyl) disulfide .The concentrate thus formed is compounded with a well treated lubricating oil of the paraffinic type, i. e. of high viscosity index varying from 85 to 105 V. I. more or less, produced either from a parafiinic crude or from a mixed base crude by dewaxing and if desired by solvent extraction or other method of treatment.

The concentrate is added to give a lubricating oil containing from .5% to 3% more or less of the calcium soap'and from about .15% to 3% more or less of the sulfide or disulfide chosen. It will be sufilcient, however, in many cases, as for instance in formulating lubricating oil for Diesel engines, to employ about 1.5% to 2% of the soap and about .5% to 2% of the inhibitor.

Instead of using the calcium soap of dichloro stearic acid we may use, in about the same proportions as the above formulations, instead of this soap the calcium soap of phenyl stearic acid or the acids produced by oxidation of petrolatum.

For motor lubricants it may not be necessary to employ the calcium soaps of the above. acids and such oils may be formulated by adding the inhibitors either direct or in the form of a concentrate to the lubricating oil.

While the above compounds are useful is lubrieating oils, they also may be used as inhibitors greases. in formulating such greases the inhibitor is added to the lubricating oil which isto be compounded with the soaps for making the grease. The manner of formulating grease is well known and conventional in this art, the in; vention in this regard being the incorporation of the inhibitors of this invention in such grease. The grease may be a lime base grease in which a calcium soap is used, a barium soap grease or a sodium soap grease. Such greases are well known in this art.

This invention also contemplates the addition of such inhibitors to gasoline. When so incorporated they have the property of stabilizing the gasoline against gum formation. Inhibitors of.

various compositions are now used and the manner of incorporation of inhibitors in gasoline is well known. The amount of inhibitor to be added to the gasoline will depend upon the nature of the gasoline and the gum content. Usualof the ly it will be found that from .5% to 3% inhibitor may be usefully employed.

The foregoing description and examples are not intended to be limiting of my invention, it being understood that various changes and modifications may be made therein without departing from the spirit of the appended claims.

1. A composition of. matter comprising a lubricating oil fraction and a compound of the gen? eral formula RrRwR where R is an aryl or alkyl aryl or a substituted aryl or alkyl aryl group, :c

. is an element taken from the group sulfur or tellurium, and R is an alkyl group.

2. A composition of matter comprising a lubricating oil fraction and a compound of the general formula RznR'xR where R is taken from the class of aryl or alkyl aryl or a substituted aryl or alkyl aryl group wherein the substituent is taken from the group hydroxy, amino, sulfide, disulfide or polysulfid'e group, and .c is an element taken from the group sulfur or tellurium, and wherein R is an alkyl group.

3. A composition of matter comprising a lubricating oil fraction and a compound of the general formula RSRSR where R is one of the groups taken from the class of an aryl or alkyl aryl or a substituted aryl or alkyl aryl group wherein the substituent is taken from the group hydroxy, amino, sulfide, disulfide or polysulfide group, and S is sulfur, and R is an alkyl group.

4. A composition of matter comprising a lubricating oil fraction and a compound of the general formula where R is a radical taken from the group of aryl, alkyl aryl or substituted aryl or alkyl aryl groups. p i

5. A composition of matter comprising a lubricating oil fraction and a compound of the general formula where R is a radical taken irorn the group of aryl, alkyl aryl or substituted aryl or alkyl aryl groups, wherein the substituent is taken from the group of amino, hydroxy, sulfide, disulfide or polysulflde groups. I

6. A composition of matter comprising a lubri eating oil fraction and a small proportion of 2,5-dimethyl hexane-2,5-bis(p-tolyl sulfide).

7. A composition of matter comprising a lu- PHIIJP SUBKOW. 

